1. Field of the Invention
The invention relates in general to grommets for routing wire harnesses through vehicle panel apertures and more particularly to a grommet having a raised, rigid material on an insertion engagement surface for lowering the force required to mount the grommet in the aperture.
2. Discussion of Related Art
Typical grommets have historically been difficult to install in vehicle bulkhead or panel apertures because of the high friction arising between an interface region or engagement surface of the grommet and an edge or edges of the aperture during insertion. The vehicle panel is usually made of sheet metal and the grommets often made of soft rubber. The edge of the aperture tends to bite or dig into the rubber, making it difficult to slide the grommet into the sealing position. Various methods have been used to reduce the force required to mount a grommet in an aperture of the panel through which a wire harness is to be routed. Sometimes a lubricating liquid is sprayed on the engagement surface at the assembly location. The lubricant often spreads to other vehicle locations and parts, and can foul the assembly area.
Other attempts to reduce friction include finishing the engagement surface in some manner to reduce contact at the insertion interface. FIG. 1 illustrates an example of a prior art solution that configures the engagement surface to reduce friction. A grommet 10 has a generally circular flange section 12 that seals against a wet side of the panel. The wet side could, for example, be an engine compartment, and an opposite, dry side of the panel could be a passenger compartment. An annular groove 14 separates the flange section 12 from a wider end 16 of a conical section 18. The groove 14 is sized to receive an edge of the aperture through the panel. The wider end 16 of the conical section 18 presses against the dry side of the panel. The conical section 18 tapers to a narrower end 20 integral with a tubular section 22. The tubular section tightly fits around a wire harness passed through the flange and conical sections.
To mount the grommet 10 in the panel aperture, the conical section 18 is pulled through the aperture until the edge of the aperture is received in the groove 14. To provide a tight fit and seal, an outer surface 24 of the conical section 18 adjacent the groove 14 must be wider than the aperture. The grommet 10 uses circumferential ridges or stipples 26 around the conical section 18 at the location of this outer surface 24. The ridges 26 are meant to provide more flexibility to the outer surface. However, these ridges 26 can catch on the sheet metal of the panel and often make it difficult to know when the grommet 10 is seated properly.
Another attempt to reduce the contact friction is disclosed in commonly assigned, co-pending U.S. patent application Ser. No. 11/212,751, filed Aug. 29, 2005. Circumferential rows of depressions are set into the engagement surface to reduce the amount of surface area coming into contact with the aperture edge during insertion of the grommet.